TY - JOUR T1 - Regression of EGFR positive established solid tumors in mice with the conditionally active T cell engager TAK-186 JF - Journal for ImmunoTherapy of Cancer JO - J Immunother Cancer DO - 10.1136/jitc-2021-004336 VL - 10 IS - 6 SP - e004336 AU - Danielle E Dettling AU - Eilene Kwok AU - Lucy Quach AU - Aakash Datt AU - Jeremiah D Degenhardt AU - Anand Panchal AU - Pui Seto AU - Jessica L Krakow AU - Russell Wall AU - Brian J Hillier AU - Ying Zhu AU - Maia Vinogradova AU - Robert B DuBridge AU - Chad May Y1 - 2022/06/01 UR - http://jitc.bmj.com/content/10/6/e004336.abstract N2 - Background Despite clinical success with T cell engagers (TCEs) targeting hematological malignancies, achieving a safe and efficacious dose in patients with solid tumors remains challenging. Due to potency, low levels of target antigen expression on normal tissues may not be tolerated. To overcome this, we engineered a novel conditionally active TCE design called COBRA (Conditional Bispecific Redirected Activation). Administered as prodrugs, COBRAs bind to cell surface antigens on both normal and tumor tissues but are preferentially activated within the tumor microenvironment.Methods A COBRA was engineered to target EGFR, TAK-186. The potency of precleaved TAK-186 relative to a non-cleavable control was assessed in vitro. Mice bearing established solid tumors expressing a range of EGFR levels were administered a single bolus of human T cells, and concurrently treated with TAK-186 and associated controls intravenously. We assessed the plasma and tumor exposure of intact and cleaved TAK-186.Results TAK-186 shows potent redirected T cell killing of antigen expressing tumor cells. In vivo efficacy studies demonstrate regressions of established solid tumors, dependent on intratumoral COBRA cleavage. Pharmacokinetic studies reveal TAK-186 is stable in circulation, but once activated is rapidly cleared due to loss of its albumin-binding half-life extension domain.Conclusions The studies shown support the advancement of TAK-186, and the pursuit of additional COBRA TCEs for the treatment of solid tumors.All data relevant to the study are included in the article or uploaded as online supplemental information. ER -